Electric apparatus



Feb. 8, 1944. H, HFRACE 2,340,898

ELECTRIC APPARATUS Filed. Nov. 29, 1941 Inventor:

Hubert H- Race,

b War/W7 7.13

y His Ac'bOr-ney.

Patented Feb. s,-1944,-

ELECTRIC APPARATUS Hubert H. Race, Schenectady, N. Y., assignorto General Electric Company, a corporation of New York 1 Application November 29, 1941, Serial No. 420,941

11 Claims.

My invention relates to an electric apparatus having an insulating fluid, and to an arrangement and method of removing contaminants,

such as moisture from the insulating fluid during operation ofthe apparatus.

When an insulating fluid, such as oil or other insulating liquids are used inelectric apparatus,

such as stationary induction apparatus, the

breakdown characteristics of the insulating fluid are dependent upon the degree of purity thereof or the amount of contaminants'therein, such as water or moisture and solid floating particles. In order, therefore, to guard against the entrance of impurities into the insulating fluid the electric apparatus structure is usually thorough- 1y dried at the time of manufacture before the liquid dielectric is introduced into the apparatus .casing. Also, such apparatus has been enclosed in order to keep out moisture during operation and a suitable gas space is usually provided at the top to take care of expansion and contraction during changes in the temperature of the apparatus. In addition, it has been proposed to employ filters for removing impurities during operation of the apparatus.

' Even though great precaution is taken to dry the apparatus, and in particular the windings with their insulation, before the insulating fluid is introduced, it has been found that traces of moisture remain in the solid insulation which will pass into the fluid dielectric during operation of the apparatus. Furthermore, since small leaks maydevelop through gaskets between the cover and, the tank and between pipe gaskets, impurities may enter the apparatus during operation. Also, it may become necessary at times tric apparatus.

suitable means may be provided to obtain a sub- Another object of my inventionis to provide an improved method of maintaining the purity of an insulating liquid inan electric apparatus during operation thereof.

A further object of my inventionis to provide an improved arrangement for removing impurities from the liquid dielectric of an electric apscription referring to the accompanying drawin and the features of novelty which characterize. my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 diagrammatically illustrates a transformer system having an insulating liquid and a circulatory system which is provided with an embodiment of my invention, and Figs. 2 and 3 illustrate modifications of the system of Fig. 1.

In the arrangement illustrated in the drawing, I have provided a transformer structure with an improved arrangement for continuously cir vculating insulating liquid during operation or during an operation of a transformer and for continuously degasifying the circulating liquid to remove impurities, such as moisture therefrom. Although my invention finds efflcient application in stationary induction apparatus of the transformer type, it is to be understood that my invention may be employed in any other suitable electric apparatus which employs an insulating or dielectric liquid.

Referring to Fig. 1 of the drawing, I have illustrated a transformer structure with a fluid circulating system which includes a core ill with concentric windings ll surrounding a winding leg 12,-suitable ducts l3 being provided between the concentric windings and through which any suitable fluid dielectric may circulate. The core and coils are enclosed in a casing including a tank 14 having a cover l5 which may be attached thereto by any suitable means such s bolts IS. A conventional gasket I! may be placed between the cover and the tank. Any other stantially fluid tight system. Terminals l8 and I9 are provided of any suitable typ through which electrical connections may be made be- ,tweenpower lines and load lines and the coil sections II. The transformer is also rovided vwith a conservator or gas expansion tank 20 which is filled with liquid to any suitable le el,

such as 2|, the remainder of the tank being filled with gas so as to provide for thermal expension and contraction of the liquid. Any suit- 17, l933, and which is assigned to the same as-- signee as this present invention.

In orderto provide an improved arrangement for removing impurities, such as moisture during operation of the transformer, I provide a degasii'ying arrangement which includes a chamber 22 which has a suitable nozzle or spray means 22 at the top thereof. The spray 23 is inturn connected to the transformer tank through pipes from the nozzle 23. The portion of the chamber- 22 normally filled with liquid is connected to the transformer tanlr. through pipes 21 and 28.

Thus the casing H, tank 20, chamber 22, and connecting parts provide an enclosed fluid system including a liquid portion and a gas portion in contact with the liquid. Any suitable arrangement, such as a pump 30 may be provided for forcing the liquid from the tank through the pipes 26 and 25 to the nozzle and out the bottom of the degasifying chamber and through the pipes 21 and 28 back into the tank '20. The pump 30 may be of any suitable construction and is connected between the pipes 211 and, 28 which has its intake end connected to the pipe 21 and its exhaust end connected to the pipe 28. The pump may be rotated in any suitable manner, such as by an electric motor 3 i In order to control the energizatlon of the pump motor Si in response to operation of the transformer I provide a relay 32 of any suitable type having contacts 33 which when closed will connect the pump motor 3i across a suitable sourceof electric supply 34 through conductors 35, 36, and '37. The relay 32 has an operating coil which may be energized in response to operation of the transformer in any suitablemanner, such as by a connection to a current transformer 38 which will be energized on the passage of current through the load cable 39. A switch 40 is also provided in the line 31 of the pump motor which switch is adapted to close through the operation of a float it when the level of the liquid is at the 1evel26 as shown in the drawing, or above that level, the contacts 40 being adapted to open to deenergize the pump motor whenever the level of the liquid in the degasifying chamber 22 lowers below the level 28.

In order to provide an arrangement for removing impurities such as water or moisture from the gas in the top of the degasifying chamber 22 I provide a water or moisture removing device 45 which may be of any suitable type, such as having activated aluminum particles 46 therein which have well known deliquescent properties. One end of the water removing arrangement 45 is connected to the portion of the gas expansion chamber which is normally filled with gas by a pipe 4'! and the. other end of the water removing device 45 is also connected to that portion of the chamber 22 which is normally filled with gas by the pipes 58 and 49. A suitable pump 50 having an operating motor is employed, the'intake end of the pump being connected to the pipe 48 and its exhaust end being connected to the pipe 49 for circulatin gas from the degasifylng chamber through the water removing means and back into the degaslfying chamber. The pump motor is also operated in response to energ'ization of the transformer through contacts 52 which are in turn operated by energization of the relay 32 but it is, of course, to be understood that the pump motor 5| as well as the motor 3| may be operated in response to anyother suitable condition or during any'operation interval of the electric apparatus. a

It will, therefore, be seen that upon operation of the transformer, the pump 30 will be operated so as to continuously circulate the liquid dielectric through the degasifylng chamber and back into the transformer tank. A conventional filter 53 may also be connected in the lines 2d and for filtering out solid floating contami hates. By correlating the characteristics of the pumps 20 and 50, any suitable pressure drop may be provided between the spray nozzle 23 and the gas in the degasifying chamber surrounding the spray. With a sufficient pressure differential ob- V taining, such as one atmosphere, gas in them;-

uid which is sprayed will be liberated or removed and the liquid will fall into the bottom of they degasiiying chamber and be drawn out through the pipes 21 and 28 and returned to the transformer, the returned liquid being substantially free of any traces of moisture. The water vapor will then be drawn elf-through the a pipe 411 with the rest of the gas, the moisture being removed from the gas by the water removing arrangement within the chamber 45. The dry gas will then be returned into the degasiiying chamber through the pipes 48 and 49 and pump 50. By returning the dry gas to the degasifying chamber the pressure therein may be maintained within any suitable limits. Even though continual circulation of the li uid through the chamber 22 may cause the dissolved gas to come into equilibrium with the gas in the chamber 22, water vapor present in the fluid passing through the nozzle 23 will be liberated since the water vapor is being constantly removed. The idea of maintaining the dissolved gas in a state of equilibrium with the gas in the expansion chamber during transient conditions of temperature and pressure so as to maintain the pressure within the fluid system within predetermined limits and spraying to prevent bubble formation during rapid decreasing pressure conditions is a feature of the invention described and claimed in application S. N. 420,943, Paluev,

: in the line 55 for controlling the passage of gas from the bomb to the chamber 28.

. Instead of continually circulating gas in the' the bomb 54 at approximately the same rate as gas is withdrawn by the pump 51. The rate at which the gas is withdrawn through the pump 51 may be controlled by controlling the speed of the pump l'l, and-the rate at which the gas Modifications of the particular arrangementswhich I have disclosed embodying my invention will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular arrangements set forth and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim asnew and desire to secure by Letters Patent of the United States is:

1. An electric apparatus including an insulating liquid, means for continuously circulating a portion of said liquid during operation of said apparatus, de asiiying means in the path of said circulatio means for removing gas from said circulating liquid, means for removing moisture from the removed gas, and means for restoring 'the dried as to said apparatus.

2. An electric apparatus including an insulating liquid, means for continuously circulating a portion of said liquid during operation of said apparatus, filter means in the path of said circulating, liquid for removing solid floating contaminants, degasifying 'means in the path of said circulating liquid for removing gas from said circulating liquid, moisture removing means, and

,means for passing the removed gas through said moisture-removing means and for restoring the dried gas to the liquid circulating system.

3. An electric apparatus comprising an insulating liquid, means for continuously circulating a portion of said liquid during operation of said apparatus, filter means in the path ofsaid circulating liquid for removing solid floating contaminants, degasifying means in the path of said circulating liquid for removing gas from said circulating liquid, moisture removing means, means for passing the removed gas through said moisture removing means, and means connecting said degasii'ying means and said moisture removing means for returning the dried gas to said degasifying means.

4. An electric apparatus including an enclosing tank, an insulating liquid therein, a degasifying chamber having spray means, 'means for fluidly connecting said tank and said spray means. means for'fluldly connecting said cham-' ber with said tank. pump means operable upon an operation of said apparatus for circulating liquid through said spray means into said chamber an'dback to said tank, moisture removing means, means for fluidly connecting said chamber with said moisture removing means, and pump means for circulating gas removed from spraying it in the portion of said chamber filled with gas, means for fluidly connecting the liquid portion of said chamber withsaid tank so that the degasified liquid may be returned to said tank, water removing means, and means for circulating said gas from said gas portion of said chamber through said water removingmeans and back to said gas portion of said chamber.

6. An electric apparatus having core and coils, an enclosing tank, a liquid dielectric therein, a degasifying chamber having a portion normally filled with liquid and the remainder with gas, spray means in the gas portion of said chamber, pipe means connecting said spray means with said tank and for connecting the liquid portion of said chamber with said tank, pump means in said pipe means for forcing liquid through said spray means and back to said tank, means for controlling said pump means in response to the level of liquid in said chamber, and means for drying gas removed from said liquid in said the liquid through said moisture removing means and back to said chamber.

5. An electric apparatus having core and coils, an enclosing tank, an insulating liquid therein,

a degasifying chamber having a portion normally filled with liquid and the remainder with gas. means for removing liquid from said tank and chamber.

'7. The method of maintain-ing the purity of an insulating liquid within an electric apparatus during an operation of the apparatus which includes removing a portion of said liquid, filtering said portion to remove solid floating contaminants, degasifying said portion, removing ,moisture present in the gas liberated during the degasifying step, and returning the degasifled portion to the apparatus.

8. An electric apparatus including an insulating liquid, degasifying means, means for circulating a portion of said liquid through said degasifying means during an operation of said apparatus for liberating gas from said circulating liquid, and means for drying the gas liberated by said degasifying means during the operation of said apparatus.

- 9. An electric apparatus including an insulating liquid, degasifying means, means 'for continuously circulating a portion of' saidliquid through said degasifying means during operation of said apparatus for removing gas from said circulating liquid, means for continuously with 83s portion.

11. An electric apparatus including an insulating liquid, degasifying means, means for continuously circulating a portionzof said liquid throughsaid degasifying means during opera tion of said apparatus for removing gas from -the circulating liquid, means for continuously withdrawing the removed gas from said densitying means during operation of said'apparatus, and means for introducing gas into said apparatus for replenishing the gas in said electric apparatus withdrawn from said degasii'yins means.

- HUBER! 1!. RACE. 

